Hydraulic power unit



March 30, 1954 ATTO R N EYS Patented Mar. 30, 1954 HYDRAULIC POWER UNITBenjamin N. Ashton and Eugene V. Barkow,

Kingston. N. Y., assignors to rated, Kingston, N. Y

Ware

Electrol Incorpoa corporation of Dela- Application May 28, 1949, SerialNo. 95,944

(Cl. 10S-223) 9 Claims.

This invention relates to hydraulic power units and it relatesparticularly to a unitary hydraulic system for generating, accumulatingand supplying hydraulic power which is useful in installations, such asfor example, guided missiles and the like requiring compact andlightweight hydraulic power systems.

In accordance with the present invention, such a unit .may include amotor-driven pump which delivers liquid under pressure to a reservoirand accumulator structure .from which it may be supplied under thecontrol of a suitable selector valve to a hydraulic jack or otherhydraulic motor forming a part of the unit.

A particular feature of the system is a reservoir and accumulator unitfor the liquid which is effective to maintain a high liquid pressuretherein after the manner of an accumulator and at the same time serve asa reservoir for supplying liquid to the intake port of the pump. Thisreservoir and accumulator unit is so constructed and arranged that italways aiiords a supply of liquid to the intake of the pump, and,regardless of its position or inclination, delivers the liquid thereinto the intake of the pump so that there is little or no danger of thepump drawing in air from the system and delivering it to theaccumulator.

A typical unit of the type described generally above may be of asuitable size to be used in guided missiles and other small aircraft,boats and the like, and because of its unitary self-containedconstruction, it can be readily installed and replaced in the devicewithout extensive con necticns between the several elements making upthe system.

For a better understanding of the present invention, reference may behad to the accompanying drawing, in which:

The single gure illustrates in elevation and partially in longitudinalsection a hydraulic system of the type embodying the present invention.

While the invention will be described with reference to the use of theunit with a reciprocating hydraulic jack and a slide type of selectorvalve, it will be understood that the invention may be practiced withequal facility with a versibie rotary hydraulic motor and other types ofselector valves without departing from the invention.

Referring now to the drawing, a typical unit may include an electricmotor lil, preferably ci small size and high energy output, which isutilized to drive a pump i i of the gear or lobe type so as to providepressure at the pressure port l2 of the pump. The motor and pump may becon nested by means of a bracket i3 to the casing lil of a combinedreservoir and accumulator. The casing it, as illustrated, provided atone end with a valve member i5 which is adjacent to and connected with ahydraulic jack i5 for control ling the operation of the latter, as willbe described hereinafter.

The casing it of the combined reservoir and accumulator is of generallycylindrical shape in end View and is provided with a thickened wallportion l'i in which the liquid passages it and i9 are formed. Thepassages lil and |53 extend through the bracket l 3 and are connected,respectively, to the pressure or discharge port i2 of the pump and theintake port 253 of the pump. The port l2 is connected by means of thepassage I8 to the interior of the casing Irl near the left-hand endthereof so that the liquid under pressure is forced into the compartment2l between the lefthand end of the casing and the piston 22 which ismovable axially of the casing i4.

The return passage i9 is connected to the interior of the casing it bymeans of a return passage 23 on the right-hand side of the piston member2li which is reciprocable lengthwise of the casing. The passage Il) isfurther connected to a port in the selector valve l5 as describedhereinafter.

piston members 22 and 2d are adapted to reciprocate axially of thecasing lil and are utiliaed to keep the compartment 25 to the right ofthe piston 2t completely full of liquid by varying the size of thecompartment. Likewise, the compartment 2| is kept full of liquid underpressure by the movement of the piston 22. The casing lil is divided bymeans of a fixed partition 25 sealed to the wall of the casing by meansof a suitable sealing ring 2l. The partition 26 is keyed or otherwisesecured to the casing.

The piston 22 is provided with an annular spacing sleeve 28 whichengages against the partition 2li when the piston has moved to its limitposition to the right.

The piston 2li is provided with a plunger rod 29 which is slidable in anaperture :it in the partition 2li. The rod 29 is maintained in sealingrelation to the partition 26 by means of the sealing ring si mounted inthe partition and engaging the plunger 29.

The space between the piston 22 and the partition 25 receives gas underpressure which is introduced through an air check valve 32 mounted inthe wall of the casing lll and communicating with the compartment orspace 33. The pressure of the air or gas in the compartment 33 isrelated to the liquid pressure on the pressure side of the pump so thatas the pressure and volume of liquid in the compartment varies, thepiston will move to the right or left, thereby keeping the compartment2l full of liquid at substantially the desired pressure. Thus, if thepressure in the gas or air chamber 33 is in the vicinity of 700 poundsper square inch, the liquid in the chamber 2l will be maintained underthe same pressure as the air. In this way, the compartment 2l serves asan accumulator for the liquid under pressure.

Inasmuch as it is desired to maintain liquid at the intake 28 of thepump II at all times, the liquid in the reservoir or compartment is alsomaintained under pressure by means of the air or gas pressure in thecompartment 33. It is unnecessary to maintain the liquid in thecompartment 25 under as high a pressure as the liquid in the compartment2I and it is for this reason that the plunger 29 is provided. Thisplunger is acted upon by the air pressure, and, by regulating thecross-sectional area of the piston, a desired pressure may be applied tothe liquid in the reservoir 25. In a typical example, the air pressurein the chamber 33 may be 700 pounds per square inch while the area ofthe plunger 29 is such that the pressure on the liquid in the reservoir25 is in the vicinity cf 2O pounds per square inch. Due to the pressureexerted on the plunger 29, the piston 24 will be moved to the right orleft depending upon the volume of the liquid in the compartment to keepthe latter full of liquid under the desired pressure. Regardless of thepositi^n of the unit as a whole, liquid will at all times be supplied tothe intake or suction port 25 of the pump.

The liquid from the reservoir 2I may be supplied to any desired type ofhydraulic motor under the control cf a selector valve. In the form ofvalve and motor illustrated the selector Valve I5 is of the slide typewhile the motor I5 is of the hydraulic jack type.

The casing in which the valve I5 and the jack I6 are housed may be ablock of metal of any desired shape having an end portion 35 threadedinto and closing the left-hand end of the casing I4.

The valve I5 includes a bore 36 extending through the block 31 forreceiving the slide valve plunger 38. The slide valve may consist of acylindrical portion 39 having a pair of spaced apart flanges 40 and 4Iand an axial bore 42 therein communicating with apertures 43 and 44disposed outside the anges 4Q and 4I. The

plug 38 may be provided with actuating rods 45 and 45 at opposite endswhich extend through closure caps 41 and 45 threaded into enlargedopposite end portions of the bore 35. The plunger is normally urgedtoward a neutral position corresponding to the position shown in thedrawing, by means of coiled springs 49 and 50 bearing against washerswhich are loosely mounted on the rod-s 45 and 45 and engage the ends ofthe plunger when the latter is centered. Upon movement of the plunger 38in one direction or another, the washer at one end is restrained byengagement with a shoulder in the end of the bore 35 and the spring atthe opposite end is compressed, tending to return the plunger tocentered position.

The casing 31 is provided with a series of four grooves 5I, 52, 53 and5A; circumferentially of the bore 33. which form the ports of the valve.The port 52 is connected to a passage 55 communicating with the interiorof the chamber 2I. The port 54 communicates with a passage 56 in theblock 31 which is connected to the return conduit I9.

The port 5I is connected by means of a passage 51 to the interior of thejack IG on one side of the piston 53 in the jack. The other port 53 isconnected by means of a passage 59 to the interior of the jack cylinderon the opposite side of the piston 58. The piston 58 may be xed.

to a reciprocable shaft 60 which is guided for axial movement in closureplugs 5I and 62 at opposite ends of the bore 63 in the jack cylinder.

In the neutral or centered position of the plug 38 of the selector ValveI5, the rings or flanges 40 and 4I cover completely the ports 5I and 53so that the fluid under pressure at the port 52 cannot pass into eitherend of the jack I6. If the valve plug 38 is moved downwardly from theposition shown, the ports 5I and 53 are completely or partiallyuncovered so that liquid under pressure iiows through the port 52, pastthe plunger 38 into the port 53 and then into the cylinder 83 below thepiston 58, forcing it upwardly. At the same time, the port 5I isuncovered and the flange 40 is interposed between the ports 5I and 52 sothat the liquid above the piston 58 flows through the passage 51, port5|, aperture 44, passage 42, aperture 43, port 54 and through the returnpassages 56 and I9 to the suction or intake side of the pump and to thecompartment 25.

If the valve plug 38 is moved upwardly, the ports 5I and 53 are againuncovered but communication is established between the port 52 and theport 5I so that liquid Under pressure is delivered to the cylinder 53above the piston 58 to force it down. At the same time, liquid iiows outthrough the passage 59, port 53 around the outside of the plunger to thepassage 54 and to the return lines 56 and I9.

Liquid cannot flow through the valve passage 42 for the valve flange 40is disposed above the passage 5I and prevents short circuiting of the i'liquid.

In order to avoid the accumulation of too high a pressure in thecompartment 2|, a relief valve 65, set to open under a pressurecorresponding to the pressure in the air chamber, may be interposedbetween the pressure and return lines I8 and I9. Likewise, in order toprevent back ow of liquid from the accumulator compartment 2| to thepump, a check valve 6G may be interposed in the pressure line I8.

The above-described apparatus provides a complete hydraulic pressuregenerating and actuating mechanism which is usable in any position sothat it is especially adapted for use in installations which may assumemany different positions in operation. Also, because of the arrangementof the reservoir and the accumulator unit, a most compact system may beprovided which is completely self-contained requiring no other hydraulicconnections than those described above. Such an arrangement greatlyfacilitates its installation in many types of devices and affords asimple, yet highly effective hydraulic system for controlling theoperation of rudders, wing Iiaps and the like in guided missiles andother similar devices.

It will be understood, of course, that the size of the devices may bevaried as the purpose demands and that other arrangements and relations,than those disclosed, may be utilized as required. Therefore, the formof the invention described above should be considered as illustrativeand not as limiting the scope of the following claims.

We claim:

l. In a hydraulic power unit, the combination of a motor-driven pumphaving an intake port and a discharge port; and a reservoir andaccumulator unit having an expansible and contractile accumulatorchamber connected to said discharge port for receiving liquid underpressure from said pump, a reservoir for receiving liquid and connectedto said intake port for supplying liquid to said pump, and separatepiston means moveable relative to each other in said chamber and saidreservoir, means to apply pressure against said piston means to movethem in said chamber and said reservoir to maintain them full of liquidunder pressure, said pressure applying means including means forapplying a lower pressure to the liquid in said reservoir chamber thanto the liquid in said accumulator chamber.

2. In a hydraulic power unit, the combination of a motor-driven pumphaving an intake port and a discharge port for supplying liquid underpressure; and a reservoir and accumulator unit having an accumulatorchamber connected to said discharge port for receiving liquid underpressure, a piston reciprocable in said chamber to vary its capacity, areservoir chamber connected to said intake port to supply liquid to saidpump, means to maintain liquid in said reservoir chamber, a pistonreciprocable in said reservoir chamber to vary its capacity and meansfor applying unequal pressures to said pistons to keep said chambersfull of liquid and the liquid in said accumulator under higher pressurethan the liquid in said reservoir chamber.

3. In a hydraulic power unit, the combination of a motor-driven pumphaving an intake port and a discharge port for supplying liquid underpressure; and a reservoir and accumulator unit having an accumulatorchamber connected to said discharge port for receiving liquid underpressure, a piston reciprocable in said chamber to vary its capacity, areservoir chamber connected to said intake port to supply liquid to saidpump,

-a piston reciprocable in said reservoir chamber to vary its capacity,means to maintain liquid in said reservoir chamber, a chamber interposedbetween said pistons for receiving gas under pres- Y sure for applyingpressure to said pistons to displace them and keep said chambers full ofliquid under pressure, and means for reducing the pressure applied tothe liquid in said reservoir chamber to a lower value than the pressureapplied to the liquid in said accumulator chamber.

4. In a hydraulic power unit, the combination of a motor-driven pumphaving an intake port and a discharge port; a reservoir and accumulatorunit having an expansible and contractile accumulator chamber, anexpansible and contractile reservoir chamber` and means for applyingpressure to said chambers tending to contract them, said pressureapplying means applying less pressure to said reservoir chamber than tosaid accumulator chamber; a connection between said pump discharge portand said accumulator chamber; a connection between said pump intake portand said reservoir chamber; and a selector valve connected to saidaccumulator chamber, said pump and said reservoir chamber forcontrolling the ilow of liquid to and from said pump, reservoir andaccumulator.

5. An accumulator and reservoir unit for receiving liquid from andsupplying it to a pump. comprising a. substantially cylindrical casing,a partition in said casing adjacent to its mid-portion dividing it intoan accumulator chamber and a reservoir chamber, pistons in said chambersmovable lengthwise thereof 0n opposite sides of said partition, meansfor introducing gas under pressure into said casing between saidpartition and the piston in the accumulator chamber, and means forapplying the pressure of said gas at reduced value to the piston in saidreservoir chamber.

6. An accumulator and reservoir unit for receiving liquid from andsupplying it to a pump, comprising a substantially cylindrical casing, apartition in said casing adjacent to its mid-portion dividing it into anaccumulator chamber and a reservoir chamber, said partition having acentrally located aperture in it, pistons in said chambers movablelengthwise thereof on opposite sides of said partition, means forintroducing gas under pressure into said casing between said partitionand the piston in the accumulator chamber, and means cooperating withsaid aperture and acting through the piston in said reservoir chamber tomaintain the liquid in said reservoir chamber under a pressure less thanthe pressure in said accumulator chamber.

7. An accumulator and reservoir unit for receiving liquid from andsupplying it to a pump, comprising a substantially cylindrical casing, apartition in said casing adjacent to its mid-portion dividing it into anaccumulator chamber and a reservoir chamber, pistons in said chambersmovable lengthwise thereof on opposite sides of said partition, meansfor introducing gas under pressure into said casing between saidpartition and the piston in the accumulator chamber, and a piston rodextending through said aperture and connected to the piston in thereservoir chamber and responsive to pressure of said gas to urge thelast-mentioned piston in a direction to maintain the liquid in saidreservoir chamber under a pressure less than the pressure on the liquidin said accumulator chamber.

8. An accumulator and reservoir unit for receiving liquid from andsupplying it to a pump, comprising a substantially cylindrical casing, apartition in said casing adjacent to its mid-portion dividing it into anaccumulator chamber and a reservoir Chamber, pistons in said chambersmovable lengthwise thereof on opposite sides of said partition, a sleeveon the piston in the accumulator chamber for maintaining thelastmentioned piston in spaced relation to said partition, means forintroducing gas under pressure into said casing between said partitionand the piston in the accumulator chamber, and means for applying thepressure of said gas at reduced value to the piston in said reservoirchamber.

9. An accumulator and reservoir unit for receiving liquid from andsupplying it to a pump, comprising an expansible and contractileaccumulator chamber, an expansible and contractile reservoir chamber,and means common to both chambers for applying gas pressure to saidreservoir chamber and to said accumulator chambers to contract them andkeep them full of liquid under pressure. said means having areas ofdifferent size exposed to the gas pressure and acting separately on saidaccumulator and reservoir chambers to maintain the liquid in saidaccumulator chamber under higher pressure than the liquid in saidreservoir chamber.

BENJAMIN N. ASHTON. EUGENE V. BARKOW.

References Cited in the file of this patent UNITED STATES PATENTS

